|Number|Builder|Entered service|Withdrawn|Notes|
|---|---|---|---|---|
|439|NZR Addington|9-1-1909|2-3-1957|Converted to 4-cylinder simple, 6-1949|
|440|NZR Addington|25-3-1909|2-3-1957|Converted to 4-cylinder simple, 7-1948|
|441|NZR Addington|10-5-1909|2-3-1957||
|442|NZR Addington|10-7-1909|4-3-1944|Converted to 4-cylinder simple, 6-1943. In Use Ohai Railway Board 1944-1968. Preserved at Feilding and District Steam Rail Society|
|443|NZR Addington|1-12-1909|2-3-1957|Converted to 4-cylinder simple, 7-1947|
|444|NZR Addington|3-2-1910|2-3-1957|Converted to 4-cylinder simple, 12-1949|
|445|NZR Addington|24-5-1910|26-5-1949||
|446|NZR Addington|30-4-1910|6-12-1946|Converted to 4-cylinder simple, 12-1946. In Use Ohai Railway Board 1946-1959.|
|588|NZR Addington|14-10-1913|2-3-1957|Converted to 4-cylinder simple, 5-1951|
|589|NZR Addington|11-11-1949|6-1949||
|590|NZR Addington|27-1-1914|2-3-1957||
|591|NZR Addington|17-3-1914|2-3-1957|Converted to 4-cylinder simple, 12-1950|
|592|NZR Addington|22-6-1914|2-3-1957|Converted to 4-cylinder simple, 10-1950|
|593|NZR Addington|3-9-1914|2-3-1957|Converted to 4-cylinder simple, 6-1950|
|594|NZR Addington|31-10-1914|2-3-1957|Converted to 4-cylinder simple, 5-1945|
|595|NZR Addington|3-12-1914|2-3-1957||
|596|NZR Addington|26-1-1915|2-3-1957|Converted to 4-cylinder simple, 12-1949|
|597|NZR Addington|1-4-1915|2-3-1957||

Question: which number was in service the least amount of time?
Answer: 589